Anti rollback device for conveyors



- Nov. 19, 1957 r P. J. KOEPNICK ET AL 3,

ANTI ROLL-BACK DEVICE FOR CONVEYORS 2 Sheets-Sheet 2 Filed March 3, 1954 FIG. 6

lNVENTORS PAUL. J. KOEPNICK EGBERT WOLDRING- ATTORNEY atent Patented Nov. 19, 1957 2,813,604 ANTI ROLLBACK DEVICE FOR CONVEYORS Paul J. Koepnick and Egbert Woldring, Grand Rapids, Mich., assignors to The Rapids-Standard Company, Inc., Grand Rapids, Mich., a corporation of Michigan Application March 3, 1954, Serial No. 413,760

4 Claims. (Cl. 192-2) This invention relates to means for preventing the rollback of conveyor belts operating on an inclined surface after the belt driving motor has been stopped. Rollback of the belt results from the weight of the articles resting on the belt at the time the motor is shut off.

One of the serious problems that has plagued the manufacturers of inclined, powered conveyors has been the tendency of the belt to roll back down the incline after the motor has been shut off. This is particularly true when the conveyor is used to move heavy articles. Recognizing that various clutches and locks could be provided to prevent this rollback, such solutions are not satisfactory. These devices are both expensive and subject to malfunction under the adverse operating conditions to which this type of equipment is frequently subjected.

It is, therefore, a primary object of our invention to provide a simple and relatively inexpensive device preventing rollback of the belt.

A further object of our invention is to provide such a device which is positive in its operation.

An additional object of our invention is to provide an anti-rollback device positively coordinated with the op eration of the belt driving motor so that it is automatically applied immediately upon de-energization of the motor and automatically released when the motor is energized.

A still further object of our invention is to provide an anti-rollback device capable of functioning satisfactorily even under extremely adverse operating conditions.

These and other objects and purposes of our invention will be immediately seen by those acquainted with the design and construction of powered conveyor equipment upon reading the following specification and the accompanying drawings.

In the drawings:

Fig. 1 is a side elevation view with our invention.

Fig. 2 is an enlarged, fragmentary, side elevation view of our invention.

Fig. 3 is a sectional elevation view taken along the plane Ill-Ill of Fig. 2.

Fig. 4 is an enlarged, fragmentary, bottom view of our invention.

Fig. 5 is a fragmentary, end elevation view of our invention.

Fig. 6 is an enlarged, fragmentary view of a modified form of our invention in which a solenoid is substituted for manual operation.

Fig. 7 is a fragmentary, sectional elevation view taken along the plane VII-VII of Fig. 6.

Fig. 8 is a wiring diagram for the modified form of our invention.

In executing the objects and purposes of our invention, we have provided a relatively large diameter pulley on the end of the motor driven shaft from which power is taken ed for driving the conveyor belt. About this pulley we have provided a loop of high friction material such as of a conveyor equipped a (belt A pivoted lever, secured at one of its ends fiice to the loop and at the other of its ends to the motor operating switch, causes the loop to be tightened about the pulley whenever the motor is de-energized and to be loosened whenever the motor is energized whether in forward or reverse direction. In a modified construction for our invention, a solenoid, wired in parallel with the conveyor operating motor, controls the operation of the brake.

Referring specifically to the drawings, the numeral 10 indicates a conveyor having a bed 11, a supporting leg 12 at its upper end and a supporting leg 13 at its lower end. Mounted within the conveyor bed is an endless belt 14 passing over a driven pulley 15 (Fig. 3) at the lower end and an idler pulley 16 at the upper end.

The driven pulley 15 is mounted on a shaft driven from the gear reducer 17. The gear reducer 17 is driven through the pulley 18 by means of a belt 19 from the pulley 20. The pulley 20 is mounted on the motor shaft 21 driven by the prime mover 22. The prime mover 22 is mounted to the underside of theconveyor bed 11. The gear reducer 1'7 is mounted on a bracket 23. The bracket 23 is in turn secured to the plate 24 mounted to the side of the conveyor bed 11. The bracket 23 spaces the gear reducer 17 from the plate 24 sufliciently to permit the pulley 18 to be mounted between the bracket and the plate (Fig. 3).

A braking pulley 30 is mounted on the motor shaft 21 between the pulley 20 and the prime mover 22. The braking pulley 30 is of substantially greater diameter than the pulley 20 to provide a large, eflt'ective braking surface.

On the same side of the conveyor bed 11 as the pulleys 18 and 20 and adjacent the prime mover 22, a bracket 31 having a depending flange is secured to the conveyor bed by any suitable means such as welding. It is also possible to make this flange integral with the conveyor bed. The depending flange of the bracket 31 has a cutout 32 approximately at its center (Fig. 2).

The braking pulley 30 preferably has a V-shaped peripheral groove for reception of the brake loop 34. The brake loop 34 is made of material having a high coeflicient of friction such as a reinforced rubber V-belt. The brake loop 34 extends approximately around the brake pulley 30 and at each end has a U-shaped anchor terminal 35 (Figs. 2 and 3). The anchor terminal 35 on the end of the brake loop 34 adjacent the gear reducer 17 passes about a bolt 36 which, in turn, is mounted on a generally U-shaped clip 37. The clip 37 is: secured to the conveyor bed 11. The braking pulley 30 and the brake loop 34 together constitute a friction brake with the pulley functioning as the brake drum and the loop as the brake band.

The opposite end of the brake loop 34 is secured to the head 40 of the lever 41. The head 40 has a downwardly depending ear through which extends a bolt 42. The bolt 42 secures the anchor clip 35 to the head 40 (Fig. 4).

The head 40 is secured to the lever 41 by a pair of bolts 43 and 43a. While the bolt 43 passes through a round opening in both the head 40 and the lever 41 and thereby acts as a pivot, the bolt 43a passes through a slot 44 in the head to permit pivotal adjustment of the head about the bolt 43. A bolt 45 secures the lever 41 to the bracket 31. The bolt 45 also serves as a pivot point for the lever.

The other end of the lever 41 is, by means of the bolt 50, pivotally secured to an arm 53. The bolt 50 extends through a slot 52 (Fig. 2) in the bracket 31 forcing the bolt 50 to take an arcuate path, which is substantially on the axis X, as the lever is pivoted about the bolt 45. The

bolt and lever are held against lateral displacement from the bracket 31 by a washer 54 riding against the outward face of the bracket. The lever 41 and arm 53 are spaced from the bracket 31 by a spacer 60 (Fig.

Behind this end of the lever and mounted to the conveyor bed is a switch 55. The switch 55 is operated through a shaft 56 which in turn mounts a switch arm 57 The lower end'of the switch arm 57 is equipped with a handle 58. At a pointslightly upwardly from the handle 58, the switch arm 57 and the arm 53 are joined by a bolt 59 surrounded by a spacer 61 extending between the two arms.

The shaft 56 of the switch is substantially below the bolt 50 thus producing oscillating movement of the bolt 50 when the switch arm 57 is rocked to either side of its center position. The lever 41 and arm 53 are, in effect, a hinged linkage for transmitting the pivotal motion of the switch handle 58 to the flexible loop 34.

Operation The switch 55in Fig. 2 is shown in off position. If the handle is moved to either the left or right, the motor 22 is energized. To facilitate operation of the conveyor, the switch is so arranged that the handle 58 moves in the same direction as the belt 14 will travel upon energization of the motor 22. If the switch handle 58 is moved to the right, the direction of the belt 14 is to the right and therefore up the conveyor bed as it appears in Fig. l. The operating direction of the belt 14 is changed by reversing the direction of rotation of the motor 22. The design of the switch is such that it is necessary to pass the switch through its off position in reversing the direction of the motor.

With the switch off and the handle 58 in the position appearing in Fig. 2 the end of the lever 41 attached to the arm 53 is in its lowermost position, thereby pulling the brake loop 34 against the brake pulley an. In this position, the brake loop prevents rotation of the brake pulley. Since the brake pulley 39 is positively engaged by means of the belt 19, to the driven pulley 15 of the endless belt 14, the endless belt 14 is also looked against movement in either direction.

If the conveyor is to be operated to the right, that is, to elevate articles as the conveyor appears in'Fig. 1, the switch handle 5% is moved to the right. Because of the difference in vertical spacing between the switch shaft 56 and the bolt Stl this results in upward movement of the arm 53. The smaller radius traversed about the shaft 56, which determines the position of the handle 58 and of the bolt 59, will necessarily force the bolt ii upwardly. This moves the head 4% downwardly thereby disengaging the belt loop 34 from the brake pulley 30. The brake pulley is then free to rotate.

It is characteristic of this type of V-belt that once contact is made, the belt will tend to draw itself in engage ment, thus, increasingly resist rotation of the brake pulley 30. This is an important factor in providing an effective brake. By means of the bolts 43 and 43a, the position of the head 40 is adjustable so that engagement between the belt loop 34 and the brake pulley S ill occurs only during the last increment of upward movement of the head 4b. This adjustability assures positive opening of the prime mover circuit, before application of the brake. Similarly, it assures positive disengagement of the brake before closure of the prime mover circuit whether forward or reverse. Thus, there can be no overloading of the prime mover due to improper timing of the brake operation.

Slight tension of he belt loop 34 is adequate to provide effective braking action, irrespective of the loading on the belt 14. By making the brake pulley 3d of substantially greater diameter than the driving pulley 2%, a substantial mechanical advantage is also obtained.

Further mechanical advantage is gained from mounting the brake pulley on the motor shaft 21 between the motor 22 and the gear reducer R7. The braking effect of the brake loop 34 is multiplied by the gear reducer. Because of this arrangement merely slight tension on the brake 2,813,604 a V r, 1

loop 34 is sufiicient to provide complete braking of the belt 14 even under severe loads. T hus, the force necessary to operate the lever 41 is slight whereby it will not interfere with operation of the switch 55.

Modification In the modification of my invention the brake is designed to operate directly by the motor control circuit. In this modification, all'of the operating structure for the brake remains-the same except a solenoid is substituted for the arms'53 and57 andtheir related parts.

The solenoid 70 is mounted to the bracket 31 at the end of the lever 41 in the same location as the arm 53 when the mechanical switch is used (Fig. 6). The solenoid "itl is mounted below'the arm 41' and is designed to push the arm up to release the brake when energized. A spring '71 bearing against the under surface of the bracket 31 urges the lever 41 downwardly. The spring '71 automatically applies the brake when'the' solenoid is de-energized. The strength of the spring 71 is' no more than that necessary to apply the brake. This reduces the necessary capacity of the solenoid '70. The solenoid 70' is energized in series withthe motor22 by means of wires 72 and 73 co-nnectedwith the motor operating wires 74 and 75 respectively (Fig. 8). The motor operating switch 76 is so located that it also controls the operation of the solenoid.

Whenever the switch "in is closed both the motor 22 and the solenoid 70 are energized. Energization of the solenoid automatically releases the brake. Opening the switch 70 automatically die-energizes both the motor 22 and the solenoid 7t), permitting the spring 71 to automatically apply the brake. The use of the solenoid has one advantage over manual operation. It will automatically apply the brake should there be a power failure. Thus, irrespective of the cause for the stopping of the motor 22, the brake will be applied.

It will be seen that while our structure is simple, it is highly eifective. The nature of the structure is such that it is relatively inexpensive to incorporate on either new or existing equipment. Performance of the structure will not be impaired by adverse operating conditions. It Will be recognized that various modifications of our invention may be made, each without departing from the principle of the invention. Each of these modifications is to be considered as included in the hereinafter appended claims unless these claims by their language expressly state otherwise.

We claim:

1. In a brake operating mechanism for a device which is driven by a prime mover and which includes a shaft for transmitting motion from said prime mover to said device, a switch controlling the actuation of said prime mover, said switch having a pivotally mounted operating handle, the combination comprising: a pulley on said shaft; a flexible loop having a high friction surface passing around said pulley; a stationary anchor secured to one end-of said loop; a lever pivotally mounted to said device; the other of the ends of said loop secured to one end of said lever; an arm pivotally secured at one of its ends to the other of the ends of said lever; attachment means securing the other end of said arm to said handle; said pivotal connections between said arm and said lever and said arm and said handle being offset from said pivotal mounting for said handle whereby rotary movement of said handle produces pivotal movement of said lever.

2. In a brake operating mechanism for a device which is driven by a prime mover and which includes a shaft for transmitting motion from said prime mover to said device, a shaft gear reducer operatively connected to said device, a switch controlling the actuation of said prime mover, said switch having a pivotally mountedoperating handle, the combination comprising: a pulley on said shaft; a fiexible loop having a high friction surface passing around said pulley; a stationary anchor secured to one end of said loop; a lever pivotally mounted to said device; the other of the ends of said loop secured to one end of said lever; an arm pivotally secured at one of its ends to the other of the ends of said lever; attachment means securing the other end of said arm to said handle; said pivotal connections between said arm and said lever and said arm and said handle being offset from said pivotal mounting for said handle whereby rotary movement of said handle produces pivotal movement of said lever; means connecting said shaft to said gear reducer.

3. In a brake operating mechanism for a device driven by a prime mover by means of a shaft control means for controlling the operation of said prime mover, a pivotally mounted operating handle for actuating said control means, the combination comprising: a pulley mounted on said shaft; a flexible loop having a high friction surface engaging said pulley; a stationary anchor at one end of said loop; a lever pivoted intermediate its ends and connected at one end to the other end of said loop; an arm pivotally secured at one of its ends to the other end of said lever and at its other end to said handle; said pivotal connections between said arm and said lever and said arm and said handle and said pivotal mounting for said handle being offset from each other whereby rotary movement of said handle produces pivotal movement of said lever.

4. In a brake operating mechanism for a device driven by a prime mover by means of a shaft, said prime mover being adapted to rotate said shaft in two directions to drive said device in two directions control means for controlling the operation of said prime mover, a pivotally mounted operating handle for actuating said control means, the combination comprising: a pulley mounted on said shaft; a flexible loop having a high friction surface engaging said pulley; a stationary anchor at one end of said loop; a lever pivoted intermediate its ends and connected at one end to the other end of said loop; an arm pivotally secured at one of its ends to the other end of said lever and at its other end to said handle; said pivotal connections between said arm and said lever and said arm and said handle and said pivotal mounting for said handle being ofiset from each other whereby rotary movement of said handle produces pivotal movement of said lever; and the axis of rotation of said handle and the axis of said pivotal connections between said arm and said lever and said arm and said handle all lie essentially on a common plane when said handle is in neutral position whereby rotation of said handle in either direction away from neutral pivots said lever in the same direction.

References Cited in the file of this patent UNITED STATES PATENTS 749,329 Sawyer Ian. 12, 1904 786,323 Stivers Apr. 4, 1905 2,661,832 Buckeridge Dec. 8, 1953 2,681,717 Spurgeon June 22, 1954 

